Sub-Track Granularity for Point-in-Time Data Reconstitution
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Solution Overview
Problem
Existing distributed storage systems face challenges in efficiently reconstituting data storage units from snapshots, particularly in managing and retrieving data portions accurately and efficiently across multiple snapshots and the underlying volume.
Innovation Solution
A method and system for reconstituting a data storage unit by initializing a reconstituted data storage unit, identifying a type-1 data structure with a bitmap, retrieving and storing portions from snapshots and the underlying volume based on bitmap settings, and completing the reconstituted unit with data from snapshots or the volume itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional snapshot reconstitution methods are used, then data can be retrieved from snapshots, but the storage footprint increases and retrieval efficiency decreases
Solution Approach 1:
The data storage unit is divided into multiple portions, each with its own bitmap bit indicating presence in the snapshot. This segmentation allows selective retrieval of only the portions that exist in the snapshot, rather than copying the entire snapshot, thereby reducing storage footprint while maintaining retrieval efficiency.
Solution Approach 2:
The invention extracts only the necessary portions from the snapshot based on the bitmap indicators. By taking out only the portions marked as present in the snapshot, the system avoids copying unnecessary data, thus reducing storage requirements while maintaining efficient retrieval of the required data portions.
2Reliability
If all portions are retrieved from snapshots, then data completeness is ensured, but storage footprint increases
Solution Approach 1:
Each portion of the data storage unit has a corresponding bitmap bit that indicates whether that specific portion exists in the snapshot. This local quality approach allows the system to retrieve only the portions that are actually present in the snapshot, ensuring data completeness for retrieved portions while avoiding unnecessary storage of portions not present in the snapshot.
3Quantity of substance
If bitmap-based selective retrieval is used, then storage footprint is reduced, but complexity of retrieval process increases
Solution Approach 1:
The bitmap structure serves itself by automatically indicating which portions are present in the snapshot without requiring complex external management. The bitmap bits act as self-contained indicators that guide the retrieval process, simplifying the overall system architecture while enabling efficient selective retrieval and reducing storage footprint.
Data Source
AI summary
A method for reconstituting a data storage unit of a volume, the method comprising: initializing a reconstituted data storage unit that includes a plurality of portions; identifying a first type-1 data structure that corresponds to the data storage unit and a first snapshot of the volume, the first snapshot being created at a first point-in-time, the first type-1 data structure including a first bitmap, the first bitmap including a first plurality of bits, each of the first plurality of bits corresponding to a different portion of the data storage unit; retrieving, from the first snapshot, one or more portions of the data storage unit that correspond to bits in the first bitmap that are set, and storing the portions that are retrieved from the first snapshot in the reconstituted data storage unit; and returning the reconstituted data storage unit.